As is shown, for example, in Patent document 1, one method of measuring methane contained in a sample gas such as exhaust gas or the like is to cause the sample gas to pass through a non-methane cutter so that hydrocarbons excluding methane that are contained in the sample gas are combusted inside the non-methane cutter.
During this combustion, in order to prevent the methane from over-combusting due to excessive oxygen, or to prevent the hydrocarbons other than methane from not combusting completely due to insufficient oxygen, it is necessary for the correct ratio of oxygen to be supplied to the sample gas.
However, in this type of gas analysis device, there are cases when, for example, the flow rate of the sample gas varies due to pulsations in the sampling pump, or due to pressure variations in the introduced sample gas or the like.
As a result of this, because there are variations in the mixture ratio between the sample gas and oxygen, the problem arises that there are also variations in the concentration and quantity of the methane being measured.
This type of problem is also evident in gas analysis devices other than those that measure methane.